Prime Minister Justin Trudeau denounced the act of "senseless violence" against Muslims who were killed while praying inside a Quebec City mosque, stating the very essence of Canada was the target of the "terrorist attack."

In a solemn statement in the House of Commons on Monday, the Prime Minister called on all community leaders to act with responsibility and restraint, thanking the rest of the world for its outpouring of support after the shooting that claimed six lives.

"Make no mistake, this was a terrorist attack. It was an attack on our most intrinsic and cherished values as Canadians, values of openness, diversity and freedom of religion," Mr. Trudeau said in a speech. "Canadians will not be intimidated, we will not meet violence with more violence. We will meet fear and hatred with love and compassion. Always."

The Prime Minister promised that Canadians will emerge more united and stronger from the attack, while responding peacefully and in adherence with the country's core values.

"It is in tragic moments like this that we must come together in order to move forward," Mr. Trudeau said. "We will not close our minds, we will open our hearts."

He offered words of reassurance to the million Canadians of Muslim faith, saying that "36 million hearts are breaking with yours."

"You enrich our shared country in immeasurable ways, it is your home," Mr. Trudeau said. "Last night's horrible crime against the Muslim community was an act of terror committed against Canada and against all Canadians."

They attended a vigil in Quebec City in memory of the victims of the attack.

Ms. Ambrose said that Quebec City is one of the safest and most welcoming cities in Canada, blasting the "cowardly" attack against a place of worship.

"This terrorist attack strikes at the very heart of one of the freedoms we cherish as Canadians, the right to practice one's faith, to worship without fear. It is the freedom to worship as you choose with your fellow believers in your community in safety and without fear," she said.

Mr. Mulcair said all Canadians are mourning alongside their "Muslim brothers and sisters."

"We promise that we will stand united and fight against the forces of hatred, bigotry, islamophobia and those who peddle the politics of fear and division," said the NDP Leader. "People today feel unsafe in their place of worship. Many feel unsafe in their communities, and that is not something we can accept."

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He added that Canada will continue to defend its values of "diversity, peace and inclusion."

"Today, our hearts are broken, but with love and hope, we come together with the shared belief that we will overcome," Mr. Mulcair said.

The events forced Mr. Trudeau to cancel two public events on Parliament Hill on Monday, and prompted the RCMP to beef up its protective detail in the provincial capital on short notice.